DETERMINATION OF BACILLUS TUBERCULOSIS. 85 



sheet and heating it without producing a brown color. It 

 is then placed in a dish containing 4 c. c. of ether or 

 chloroform, shaken until the fluid is evaporated and 

 stained as usual. If with these processes the results are 

 negative, the attempt must be repeated with a larger 

 amount of milk. One hundred grams of milk are mixed 

 with about 5 c. c. of sodium hydrate and shaken with a 

 large amount of ether in a separatory funnel until no 

 more fat goes into the solution. A sample of the ether 

 evaporated will convince one of this fact. The fat-free 

 liquid is brought into a funnel shaped glass or a sediment 

 apparatus and allowed to stand for 24 hours. After this 

 time a dry preparation of a sample of the sediment is 

 made after the manner described. 



(d) Method of T/wcnicr: 20 c. c. of milk 

 mixed with i c. c. of 50 per cent potassium hydrate are 

 placed in centrifugal tubes and then placed in boiling 

 water for about two minutes until the milk becomes yel- 

 lowish-brown. They are then removed and well shaken, 

 the mixture treated with 20 c. c. of i^lacial acetic acid, 

 again thoroughly shaken, placed in boiling water for 

 three minutes and centrifugalized 10-20 minutes. The 

 liquid above the sediment is drawn off and the sediment 

 with about 40 c. c. of hot water again centrifugalized 

 for ten minutes, and a cover-glass preparation made 

 from the sediment in the usual manner. 



(f) Method of Ilkczcitsch: 20 c. c. of milk 

 are coagulated with citric acid, and filtered. The residue 

 on the filter is dissolved in a very dilute aqueous -solu- 

 tion of sodium phosphate, mixed with about 10 c. c. of 

 ether and shaken for 10-15 minutes. The solution found 

 beneath the fat zone is drawn off, centrifugalized, and 

 a preparation of the sediment made on a cover-glass. 



The cultivation of the tubercle bacilli from milk is 

 ,]uite difficult. They grow excluded from air and light 



